701.35b Only two cards belonging to the same meld pair can be melded. Tokens, cards that aren’t meld cards, or meld cards that don’t form a meld pair can’t be melded.
Even though the copied card text instructs me to meld them into Chittering Host, the rules don't seem to care whether I actually end up with Chittering Host, they only care that the two cards form a meld pair, which Gisela and Bruna do. As far as I can tell, the words "into Chittering Host" on Graf Rats have no actual rules meaning.
Does this work? Would you end up with a melded Brisela?
The Bruna and Gisela cards in exile will meld into Brisela, Voice of Nightmares (C.R. 712.1a), since that's the result of carrying out the meld keyword action, which is merely to "put them onto the battlefield face up and combined" (C.R 701.35a); nothing in the meld keyword action refers to the name of the resulting melded permanent.
I control Graf Rats, Midnight Scavengers, Bruna, the Fading Light and Gisela, the Broken Blade. I cast Cytoshape to have Gisela become a copy of the rats, and a second cytoshape to have Bruna become a copy of the scavengers. I then move to combat, and attempt to meld the Bruna with the Gisela. The rules for meld say:
Even though the copied card text instructs me to meld them into Chittering Host, the rules don't seem to care whether I actually end up with Chittering Host, they only care that the two cards form a meld pair, which Gisela and Bruna do. As far as I can tell, the words "into Chittering Host" on Graf Rats have no actual rules meaning.
Does this work? Would you end up with a melded Brisela?
Cytoshape cannot target a Legendary Creature, so you won't be able to copy either Bruna or Gisela.Sorry, missed the second clause on Cytoshape.